I too would love this, I pick up Pokemon Blue every now and again and all it does is accentuate how better CPUs and GPU amount to shit all. That game has immensely better flow, not to mention far better music.
As for making it happen, its beyond my abilty, but this is the best idea I can come up with;
Basically rewriting all the pointers for battle flow to skip various animations. Firstly you'd want the wild encounter to go straight to the two pokemon on the field and display "Wild GASTRODON appaeared!" followed by "What will ROSERADE do?". You'd also want HP draining to be instant/sped up (change the HP/s data, I think this may be the easiest hack of them all, just isolating the address will be hard, debugger required) or to be parallel to other actions. Obviously this is easier said than done.
That said before anyone thinks of tackling this a far more useful hack would be one to make Select/L/R/(X/Start) do something on the field. Or to add a back button to the Poketch. Or remove stupid time limit from Pal Park and allow you to skip the park game.
I'm out of the loop here so if any of the above is possible please let me know.